1. Field of the Invention:
The present invention relates to a method of and an apparatus for manufacturing a laminated glass.
2. Description of the Relevant Art:
Laminated glasses are widely used in various fields, one example being an automobile windshield. One most general laminated glass available now comprises two glass sheets bonded together with an intervening layer of a thermoplastic material such as polyvinyl butyral inserted therebetween.
Such a laminated glass is manufactured by an apparatus as disclosed in Japanese Laid-Open Patent Publication No. 58-26053, for example. Two curved glass sheets which are heated to a relatively high temperature are fed together into the apparatus by a conveyor with their concave sides facing up. In the apparatus, the glass sheets are first positioned, and then the upper glass sheet is lifted. A holder mold with an intermediate film held under suction is inserted between the upper and lower glass sheets, and the intermediate film is placed on the upper surface of the lower glass sheet, whereupon the intermediate film adheres to the lower glass sheet due to the heat of the lower glass sheet. Therefore, the intermediate film has to be placed in position on the lower glass sheet before the lower glass sheet is cooled. The intermediate film positioned on the concave side of the curved lower glass sheet often tends to develop wrinkles.
Japanese Laid-Open Patent Publication No. 62-202843 shows another apparatus for manufacturing a laminated glass. According to this apparatus, two glass sheets are separately fed by a conveyor, and then positioned in respective separate locations. Then, an intermediate film is put on one of the glass sheets, and the other glass sheet is placed on the intermediate film. Consequently, the two glass sheets are first positioned, and thereafter the intermediate film is placed on one of the glass sheets, after which the other glass sheet is brought over the intermediate film. When these other manufacturing steps are carried out after the two glass sheets have been positioned, however, the glass sheets are apt to be misaligned with respect to each other.
An intermediate film for a laminated glass is required to be finally equalized in dimensions and shape to glass sheets between which it is sandwiched. Devices for cutting off the intermediate film to desired dimensions and shape are disclosed in Japanese Laid-Open Patent Publications Nos. 59-3052 and 61-297009, for example. In the disclosed devices, after an intermediate film has been sandwiched between two glass sheets, the marginal portion of the intermediate film which protrudes out of the glass sheets is cut off by a cutter. If the cutter hits an edge of the glass sheet, then the edge of the glass sheet may be broken or the cutter itself may be damaged. Another cutting process, which is disclosed in Japanese Laid-Open Patent Publication No. 60-180942, employs a water jet for cutting off an intermediate film only. While the water jet does not damage the glass sheets which sandwich the intermediate film therebetween, a water draining system required by the use of the water jet makes the overall apparatus complex and large in size.